Indoor fogging is only beneficial in the contact zone; head high to knees. Because most disinfectants are toxic, corrosive or a respiratory hazard, you have to be pretty careful where and how you spray. It is also a temporary knock down, NOT a cure and it works best on cleaned surfaces where the biofilm has been disrupted.
So I guess it all boils down to what your friend is saying and claiming. I am offering it to a local nursing home that is worth thousands/year to me and I make it clear that no claims are being made. I am also offering it to them at only slightly above my costs, because these $145/room guys are *ssholes.
My reasoning is that it will only help if they can afford regular applications. Also, I am a crap brokedick businessman with a soft heart for the elderly. Curses!